TEE FLORA 



Seven hundred and six species of flowering plants and ferns have 

 been collected on the Patuxent Research Refuge by the writer, including 

 93 grasses, 61 sedges, 79 composites, 46 trees, and 55 shrubs and woody 

 vines. All hut 7 of the species are included in Hitchcock and Standi ey's 

 1919 Flora of the District of Columbia and Vicinity (or its 1930 Supple- 

 ment byMcAtee), which describes a total of 1771 species. This is a rich 

 flora considering that so many plants of the Washington region are re- 

 stricted to the Piedmont Plateau or to the Potomac River Valley. 

 A number of species listed in the "District Flora" as occurring only on the 

 Piedmont Plateau have been found to be common on and in the vicinity of 

 the Patuxent bottoms. The Piedmont-derived soil and the continuity of 

 the bottom lands from the lower Piedmont Plateau through the Coastal 

 Plain help to explain this distribution. Although Sanguinaria canadensis 

 has been identified from growing plants on the refuge, it is the only species 

 in the following list that is not yet represented by one or more permanently 

 filed specimens. Possibly 100 additional species could be listed in 2 or 

 3 more years of collecting, but there are not many common plants, with the 

 exception of certain composites, carices, and panicums, that have been 

 overlooked. 



L ist of Plants 



"West," "east," and "south" (W, E, and S, respectively), refer to 

 the three separately fenced tracts of the refuge. Numbers in parentheses, 

 except, as otherwise noted, refer to plants collected by the writer; identi- 

 fications other than those by the writer are so indicated. 



POLYPODIACEAE: 



Asplenium platyneuron (L.) Oakes. — Occasional; W, S; hedgerows and 

 former clearings. (5155) 



Athyrium asp lenioides (Michx.) Desv. — Occasional; W; terrace forest, 

 ( 5248T" 



Dennstaedtaa punctilobula (Michx.) Moore. — Occasional; W, S; mostly 

 terrace forest. (5438) 



Dryopteris cristata (L.) A. Gray. — Occasional; W; swamp forest. (5055) 



D. hexagonoptera (Michx.) C. Chr. — Occasional; W; Well-drained bottom- 

 land forest. (5310) 



P. marginal is (L.) A. Gray. — Rare; W, S; terrace and slope forest. 

 ( 5054) 



D. noveboracensis (L.) A. Gray. — Common; W, S; terrace forest. (5423) 



D. spinulosa (Muell.) Kuntze, var. intermedia (Muhl.) Underw. — Occa- 

 sional; W; terrace forest. (5056, det. W. R. Maxon) 



D. thelypteris (L. ) A. Gray. — Occasional; W, E, S; open shrub swamp. 

 " (5501) 



Onoclea sensibilis L. — Occasional; W, E; wet meadow. (5586) 



Polystichum acrostichoides (Michx.) Schott. --Occasional.; W, E, S; 

 terrace and slope forest. (5445) 



Pteridium latiusculum (Desv.) Maxon. — Common; W, E, S; terrace (rare), and 

 slope and upland forest. (5608) 



Woodwardia areolata (L.) Moore.— Common; W, E, S; swamp forest. (5500) 



W. virginica (L.) Sm.-- Rare: W; shrub swamp. (5503) 



10 



! 



